Preimplantation Genetic Screening
Preimplantation Genetic Screening (PGS) is a test done on fertilized embryos before implantation. This procedure makes it possible to choose only the embryos with the right number of chromosomes from all of the embryos made by a patient in a given period of assisted reproduction.
Using array Comparative Genomic Hybridization (aCGH), we can look at all 24 types of chromosomes. This way, we can rule out fetal aneuploidy before implantation.
When is PGS done?
Advanced Maternal Age
- The chance of finding abnormal chromosomes increases as the mother ages. Most embryos with the wrong amount of chromosomes don't implant in the uterine lining, or they miscarry in the first three months (first trimester).
- About 50% of all miscarriages are caused due to abnormalities in the chromosome. 68% of embryos in repeated miscarriages have something wrong with their chromosomes, and 15% of women have all chromosomally abnormal embryos.
Implantation Failure
- There is a risk for couples who don't have any chromosomal abnormalities but still make eggs with abnormal chromosomes that don't implant grow in the uterus.
Male Factor
- For a man to be able to have children, he needs to have enough and good quality sperm.
- Using PGS to check for aneuploidy during IVF can double the chance of getting pregnant. PGS is more successful at making babies than FISH (Fluorescent In Situ Hybridization).
- It has been scientifically proven that ArrayCGH is better than FISH. FISH can only look at a small number of chromosomes, but aCGH can look at all 24 chromosomes and find aneuploidies.
Frequently Asked Questions
Preimplantation genetic screening for structural chromosome rearrangements is used to find possible chromosomal abnormalities in the developing embryos. Chromosomal disorders are caused by changes in the order of chromosomes, such as translocations, inversions, and deletions.
PGT can make sure that the embryo chosen for transfer has the right number of chromosomes. This makes it less likely that the IVF cycle will fail and less likely that the pregnancy will end early.